Thermal half-select printing matrix



p 1969 J. L. JANNING THERMAL HALF-SELECT PRINTING MATRIX Filed June 19, 1967 INVENTOR JOHN L. JANNING BY Q 3 W44 .W W W H15 ATTORNEYS United States Patent 3,466,423 THERMAL HALF-SELECT PRINTING MATRIX John L. Janning, Dayton, Ohio, assignor to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Filed June 19, 1967, Ser. No. 646,888 Int. Cl. Hb 3/02 US. Cl. 219-216 3 Claims ABSTRACT OF THE DISCLOSURE Thermal half-select printing matrices in which printing on an adjacent heat-sensitive material occurs only at those matrix points which have coincident electrical current flowing through crossing electrically resistive thermal printing conductors which define those points.

Background of the invention Full-select thermal printing matrices employed in the prior art must have an isolation diode for each electrical selection conductor that is employed in order to prevent sneak currents and to isolate one matrix element from another. The thermal half-select printing matrices of the present invention eliminate the necessity of supplying an isolation diode for each electrically resistive thermal printing conductor of a thermal printing matrix.

Summary Thermal half-select printing is accomplished by coincident current energization of electrically resistive thermal printing elements.

Brief description of the drawing FIGURE 1 is a perspective view of one embodiment of the present invention, in which row andcolumn electrically resistive thermal printing conductors "are located on separate substrates.

FIGURE 2 is a perspective view of another embodiment of the present invention, in which row and column electrically resistive thermal printing conductors are located on a common substrate.

FIGURE 3 is a perspective view of an alternate electrically resistive thermal printing conductor.

Description of the preferred embodiments The thermal half-select printing matrices of the present invention are constructed for use with thermally sensitive record material. In the embodiment of FIGURE 2, a thin electrically insulating substrate 10, which may be of any electrically insulating material, such as silicon dioxide, which is not subject to rapid heat diffusion from a heated point on the substrate, is employed. The thin electrically insulating substrate should be on the order of one thousandth of an inch thick. The complete thermal printing member 11 is then mounted on a rigid support board 13.

Electrically resistive thermal printing conductors which are on the order of 16 thousandths to 70 thousandths of an inch wide and on the order of 4 millionths of an inch thick, and which are composed of an electrically resistive material such as tin oxide, Nichrome, rhenium, tantalum, or other such materials, are aligned into columns 12 on one side of the substrate 10 and into rows 14 on the other side of the substrate 10. When the heat-sensitive side of a thermally sensitive record material 31 is brought near the substrate 10, printing may be accomplished at a matrix location, such as 22, by coincident current energization of the crossing row and column conductors that are associated with that location. Coincident electrical current is supplied by the current supply means 21 and 23 and the selection grounding transistors 27 and 29, which are selectively saturated when supplied with positive voltage selection signals on their bases. For example, if an electrical current is passed through the column conductor 15 coincidentally with an electrical current through the row conductor 16, the radiated energy at the matrix location 22 due to the current in each of the conductors 15 and 16 will add, and, consequently, printing will occur on the thermally sensitive paper 31 at this location if the thermal threshold of the thermally sensitive paper is exceeded. Energization of only one conductor will not produce sufficient energy at a matrix location to exceed the thermal threshold of the thermally sensitive paper 31. At other points of the matrix, such as the matrix points 24 and 26, where only the current through either a row conductor or a column conductor generates energy, the thermal printing threshold of the heat-sensitive paper is not exceeded, and, therefore, printing does not occur at these points.

The thermal printing paper 31 may be placed in proximity with the exposed side of the electrically insulating film substrate 10. The optimum operating characteristics are found to exist when the heat-sensitive paper 31 is positioned in its thermal printing position and the current through a column conductor is increased until printing occurs as the result of energy through the column conductor only. The current through the column conductor is then reduced by approximately 10%. The same procedure is then followed for determining the optimum operating point of a row conductor.

FIGURE 1 shows another embodiment of the present invention, in which row conductors 30 are secured on one side of an electrically insulating substrate 28. The substrate 28 is then placed behind the non-thermally sensitive side of the thermally sensitive paper 32. Column conductors 36 of an electrically resistive material are secured on one side of another electrically insulating substrate 34. The substrate 34 is positioned on the front, or heat-sensitive, side of the thermally sensitive paper 32. As in the embodiment of FIGURE 2, the row and column conductors may be interchanged if desired. The same procedure for obtaining the optimum operating characteristics which was described in conjunction with the embodiment of FIGURE 2 may also be employed in connection with the embodiment of FIGURE 1.

FIGURE 3 shows an alternate electrically resistive conductor 17, which may replace the row conductors or the column conductors of the embodiments of FIGURES 1 and 2. This conductor 17 consists of alternate areas 19 of an electrically conductive material, such as copper or gold, which are deposited over an electrically resistive substrate material 18, such as tin oxide, etc. The deposited conductive material 19 reduces the resistance along portions of the conductor 17 in which no print is desired; therefore the total energy loss of the conductor 17 is reduced, and, in addition, printing is more accurately confined tothe desired printing areas 25. External electrical connections are made to the conductive areas 37 and 39 by the conductive leads 41 and 43, respectively.

What is claimed is:

1. A thermal printing device for printing on a thermallysensitive record material, comprising:

(a) a first set of electrically resistive printing elements,

and

(b) a second set of electrically resistive printing elements crossing the first set of printing elements, to form a matrix of thermal printing locations at those portions of the printing elements which intersect, and

(c) means to selectively supply electrical current through printing elements of the first and second sets of electrically resistive printing elements, to achieve printing on a thermally-sensitive record material that is positioned adjacent the matrix of thermal printing locations in the vicinity of those thermal printing locations which are formed by an intersecting portion of a printing element of the first set and an intersecting portion of a printing element of the second set when both of the crossing printing elements at a thermal printing location are coincidentally conducting current, wherein the electrically resistive printing elements of at least one of the sets of the printing elements each comprises an electrically conductive path of alternately arranged high-resistance portions and low-resistance portions, and the high-resistance portions define the thermal printing locations of the matrix.

2. A thermal printing device for printing on a thermallysensitive record material, comprising:

(a) a first set of electrically resistive printing elements,

and

(b) a second set of electrically resistive printing elements crossing the first set of printing elements, to form a matrix of thermal printing locations at those portions of the printing elements which intersect, and

(c) means to selectively supply electrical current through printing elements of the first and second sets of electrically resistive printing elements, to achieve printing on a thermally-sensitive record material that is positioned adjacent the matrix of thermal printing locations in the vicinity of those thermal printing locations which are formed by an intersecting portion of a printing element of the first set and an intersectments crossing the first set of printing elements, to form a matrix of thermal printing locations at those portions of the printing elements which intersect, and

(c) means to selectively supply electrical current through printing elements of the first and second sets of electrically resistive printing elements, to achieve printing on a thermally-sensitive record material that is positioned adjacent the matrix of thermal printing locations in the vicinity of those thermal printing locations which are formed by an intersecting portion of a printing element of the first set and an intersecting portion of a printing element of the second set when both of the crossing printing elements at a thermal printing location are coincidentally conducting current, wherein the first set of electrically resistive printing elements is mounted on one side of a non-conductive substrate, and the second set of electrically resistive elements is mounted on the other side of the non-conductive substrate, and the electrically resistive printing elements of at least one of the sets of the printing elements each comprises an electrically conductive path of alternately arranged high-resistance portions and low-resistance portions, and the high-resistance portions define the thermal printing locations of the matrix.

References Cited UNITED STATES PATENTS ing portion of a printing element of the second set 2,610,102 9/1952 Glilendanflel t 346-34 when both of the crossing printing elements at 21 2,686,222 8/1954 Walker et a1 0-166 X thermal printing location are coincidentally conduct- 3,145,071 8/1964 V n e 346-46 ing Current, wherein the first set of electrically 3,214,765 1 1965 Bond 340-16 sistive printing elements is mounted on one id f a 3,219,993 11/ 1965 tZ 34676 X non-conductive substrate, and the second set of elec- 35 3,312,979 4/1967 Della Torre et a1 6- trically resistive elements is mounted on the other side of the non-conductive substrate. 3. A thermal printing device for printing on a thermallysensitive record material, comprising:

(a) a first set of electrically resistive printing elements,

and (b) a second set of electrically resistive printing ele- JOSEPH V. TRUHE, Primary Examiner C. L. ALBRITTON, Assistant Examiner U.S. Cl. X.R. 

